Species: Eurhopalothrix gravis

Distribution:

Mexico, Honduras (type locality), Costa Rica (Atlantic lowlands), Dominica, Brazil (SC).

Biology:

The genus Eurhopalothrix occurs in the Neotropics and in the Indo-Australian-southwestern Pacific area (Brown and Kempf 1960). They are members of the "cryptobiotic" fauna: small, slow ants that live in rotten wood and leaf litter. They are predators, preying on small, soft-bodied arthropods (Wilson 1956, Brown and Kempf 1960, Wilson and Brown 1985).

Workers and nests are extremely difficult to see in the field, because the workers are camouflaged and very slow moving. On disturbance they freeze, often curling into a pupal position, and remain motionless for several minutes (Wilson and Brown 1985, Hoelldobler and Wilson 1986). As a result of their cryptic nature, they were considered extremely rare until the 1960's. But increasing use of Winkler and Berlese sampling has shown Eurhopalothrix to be relatively common. I encounter them in most Winkler samples from wet forest sites in Costa Rica.

I know this species from (1) a worker at the edge of the lab clearing at La Selva Biological Station, (2) a dealate queen under epiphytes in an old treefall at La Selva, and (3) a worker from a Winkler sample from Casa Eladio in the Penas Blancas Valley east of Monteverde. Brown and Kempf (1960) reported a collection of workers and alate queens from Limon Province, Hamburg Farm (F. Nevermann).

I also tentatively place under this species a dealate queen from a Winkler sample from Hitoy Cerere Biological Reserve. It is smaller than the La Selva queen, and differs significantly in sculptural details, but of all the species I currently recognize, it seems closest to gravis.

Taxonomic History (provided by Barry Bolton, 2010)

References:

Brown, W. L., Jr., Kempf, W. W. 1960. A world revision of the ant tribe Basicerotini. Stud. Entomol. (n.s.) 3:161-250.

Hoelldobler, B., Wilson, E. O. 1986. Soil-binding pilosity and camouflage in ants of the tribes Basicerotini and Stegomyrmecini (Hymenoptera, Formicidae). Zoomorphology (Berl.) 106:12-20.

Mann, W. M. 1922. Ants from Honduras and Guatemala. Proc. U. S. Natl. Mus. 61:1-54.

Menozzi, C. 1936. Due nuovi Dacetini di Costa Rica e descrizione della larva di uno di essi (Hymenoptera: Formicidae). Arb. Morphol. Taxon. Entomol. Berl.-Dahl. 3:81-85.

Santschi, F. 1923. Descriptions de quelques nouvelles fourmis du Bresil. Rev. Mus. Paul. 13:1255-1264.

Wilson, E. O. 1956. Feeding behavior in the ant Rhopalothrix biroi Szabo. Psyche (Camb.) 63:21-23.

Wilson, E. O., Brown, W. L., Jr. 1985 ("1984"). Behavior of the cryptobiotic predaceous ant Eurhopalothrix heliscata, n. sp. (Hymenoptera: Formicidae: Basicerotini). Insectes Soc. 31:408-428.